Association of bovine αs1- and β-casein using the fluorescent properties of 1,8-anilinonaphthalene sulphonate

Abstract

SummaryThe effects of NaCl, CaCl2and temperature on the emitted fluorescence of anilinonaphthalene sulphonate (ANS) in solutions of αs1- and β-casein indicated that the ANS was associated with the protein. Increased aggregation of the protein was responsible for further enhancement of the fluorescence. Addition of CaCl2to a mixture of αs1- and β-casein at 37 °C caused a greater increase in fluorescence than when αs1- or β-casein was used alone, supporting the suggestion that these 2 proteins form co-polymers with different properties from the homopolymers and indicating that hydrophobic bonding between αs1- and β-casein may be important in the presence of Ca.